1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
package query
import (
"context"
"github.com/matrix-org/dendrite/roomserver/storage"
"github.com/matrix-org/dendrite/roomserver/types"
"github.com/matrix-org/gomatrixserverlib"
"github.com/sirupsen/logrus"
)
// backfillRequester implements gomatrixserverlib.BackfillRequester
type backfillRequester struct {
db storage.Database
fedClient *gomatrixserverlib.FederationClient
thisServer gomatrixserverlib.ServerName
// per-request state
servers []gomatrixserverlib.ServerName
eventIDToBeforeStateIDs map[string][]string
eventIDMap map[string]gomatrixserverlib.Event
}
func newBackfillRequester(db storage.Database, fedClient *gomatrixserverlib.FederationClient, thisServer gomatrixserverlib.ServerName) *backfillRequester {
return &backfillRequester{
db: db,
fedClient: fedClient,
thisServer: thisServer,
eventIDToBeforeStateIDs: make(map[string][]string),
eventIDMap: make(map[string]gomatrixserverlib.Event),
}
}
func (b *backfillRequester) StateIDsBeforeEvent(ctx context.Context, targetEvent gomatrixserverlib.HeaderedEvent) ([]string, error) {
b.eventIDMap[targetEvent.EventID()] = targetEvent.Unwrap()
if ids, ok := b.eventIDToBeforeStateIDs[targetEvent.EventID()]; ok {
return ids, nil
}
// if we have exactly 1 prev event and we know the state of the room at that prev event, then just roll forward the prev event.
// Else, we have to hit /state_ids because either we don't know the state at all at this event (new backwards extremity) or
// we don't know the result of state res to merge forks (2 or more prev_events)
if len(targetEvent.PrevEventIDs()) == 1 {
prevEventID := targetEvent.PrevEventIDs()[0]
prevEvent, ok := b.eventIDMap[prevEventID]
if !ok {
goto FederationHit
}
prevEventStateIDs, ok := b.eventIDToBeforeStateIDs[prevEventID]
if !ok {
goto FederationHit
}
newStateIDs := b.calculateNewStateIDs(targetEvent.Unwrap(), prevEvent, prevEventStateIDs)
if newStateIDs != nil {
b.eventIDToBeforeStateIDs[targetEvent.EventID()] = newStateIDs
return newStateIDs, nil
}
// else we failed to calculate the new state, so fallthrough
}
FederationHit:
var lastErr error
logrus.WithField("event_id", targetEvent.EventID()).Info("Requesting /state_ids at event")
for _, srv := range b.servers { // hit any valid server
c := gomatrixserverlib.FederatedStateProvider{
FedClient: b.fedClient,
AuthEventsOnly: false,
Server: srv,
}
res, err := c.StateIDsBeforeEvent(ctx, targetEvent)
if err != nil {
lastErr = err
continue
}
b.eventIDToBeforeStateIDs[targetEvent.EventID()] = res
return res, nil
}
return nil, lastErr
}
func (b *backfillRequester) calculateNewStateIDs(targetEvent, prevEvent gomatrixserverlib.Event, prevEventStateIDs []string) []string {
newStateIDs := prevEventStateIDs[:]
if prevEvent.StateKey() == nil {
// state is the same as the previous event
b.eventIDToBeforeStateIDs[targetEvent.EventID()] = newStateIDs
return newStateIDs
}
missingState := false // true if we are missing the info for a state event ID
foundEvent := false // true if we found a (type, state_key) match
// find which state ID to replace, if any
for i, id := range newStateIDs {
ev, ok := b.eventIDMap[id]
if !ok {
missingState = true
continue
}
// The state IDs BEFORE the target event are the state IDs BEFORE the prev_event PLUS the prev_event itself
if ev.Type() == prevEvent.Type() && ev.StateKey() != nil && *ev.StateKey() == *prevEvent.StateKey() {
newStateIDs[i] = prevEvent.EventID()
foundEvent = true
break
}
}
if !foundEvent && !missingState {
// we can be certain that this is new state
newStateIDs = append(newStateIDs, prevEvent.EventID())
foundEvent = true
}
if foundEvent {
b.eventIDToBeforeStateIDs[targetEvent.EventID()] = newStateIDs
return newStateIDs
}
return nil
}
func (b *backfillRequester) StateBeforeEvent(ctx context.Context, roomVer gomatrixserverlib.RoomVersion, event gomatrixserverlib.HeaderedEvent, eventIDs []string) (map[string]*gomatrixserverlib.Event, error) {
// try to fetch the events from the database first
events, err := b.ProvideEvents(roomVer, eventIDs)
if err != nil {
// non-fatal, fallthrough
logrus.WithError(err).Info("Failed to fetch events")
} else {
logrus.Infof("Fetched %d/%d events from the database", len(events), len(eventIDs))
if len(events) == len(eventIDs) {
result := make(map[string]*gomatrixserverlib.Event)
for i := range events {
result[events[i].EventID()] = &events[i]
b.eventIDMap[events[i].EventID()] = events[i]
}
return result, nil
}
}
c := gomatrixserverlib.FederatedStateProvider{
FedClient: b.fedClient,
AuthEventsOnly: false,
Server: b.servers[0],
}
result, err := c.StateBeforeEvent(ctx, roomVer, event, eventIDs)
if err != nil {
return nil, err
}
for eventID, ev := range result {
b.eventIDMap[eventID] = *ev
}
return result, nil
}
// ServersAtEvent is called when trying to determine which server to request from.
// It returns a list of servers which can be queried for backfill requests. These servers
// will be servers that are in the room already. The entries at the beginning are preferred servers
// and will be tried first. An empty list will fail the request.
func (b *backfillRequester) ServersAtEvent(ctx context.Context, roomID, eventID string) (servers []gomatrixserverlib.ServerName) {
// getMembershipsBeforeEventNID requires a NID, so retrieving the NID for
// the event is necessary.
NIDs, err := b.db.EventNIDs(ctx, []string{eventID})
if err != nil {
logrus.WithField("event_id", eventID).WithError(err).Error("ServersAtEvent: failed to get event NID for event")
return
}
// Retrieve all "m.room.member" state events of "join" membership, which
// contains the list of users in the room before the event, therefore all
// the servers in it at that moment.
events, err := getMembershipsBeforeEventNID(ctx, b.db, NIDs[eventID], true)
if err != nil {
logrus.WithField("event_id", eventID).WithError(err).Error("ServersAtEvent: failed to get memberships before event")
return
}
// Store the server names in a temporary map to avoid duplicates.
serverSet := make(map[gomatrixserverlib.ServerName]bool)
for _, event := range events {
serverSet[event.Origin()] = true
}
for server := range serverSet {
if server == b.thisServer {
continue
}
servers = append(servers, server)
}
b.servers = servers
return
}
// Backfill performs a backfill request to the given server.
// https://matrix.org/docs/spec/server_server/latest#get-matrix-federation-v1-backfill-roomid
func (b *backfillRequester) Backfill(ctx context.Context, server gomatrixserverlib.ServerName, roomID string, fromEventIDs []string, limit int) (*gomatrixserverlib.Transaction, error) {
tx, err := b.fedClient.Backfill(ctx, server, roomID, limit, fromEventIDs)
return &tx, err
}
func (b *backfillRequester) ProvideEvents(roomVer gomatrixserverlib.RoomVersion, eventIDs []string) ([]gomatrixserverlib.Event, error) {
ctx := context.Background()
nidMap, err := b.db.EventNIDs(ctx, eventIDs)
if err != nil {
logrus.WithError(err).WithField("event_ids", eventIDs).Error("Failed to find events")
return nil, err
}
eventNIDs := make([]types.EventNID, len(nidMap))
i := 0
for _, nid := range nidMap {
eventNIDs[i] = nid
i++
}
eventsWithNids, err := b.db.Events(ctx, eventNIDs)
if err != nil {
logrus.WithError(err).WithField("event_nids", eventNIDs).Error("Failed to load events")
return nil, err
}
events := make([]gomatrixserverlib.Event, len(eventsWithNids))
for i := range eventsWithNids {
events[i] = eventsWithNids[i].Event
}
return events, nil
}
|
